The Prince of Wales cannot defend all faiths because the differences between them makes such a position untenable, a senior Anglican bishop has said.
Dr Nazir-Ali writes for the Church of England newspaper
The Bishop of Rochester, Dr Michael Nazir-Ali, said all faiths could not be defended because of serious differences between various religions.
He said Prince Charles would be obliged to take an oath to defend the Christian church if he succeeded to the throne.
Dr Nazir-Ali has also warned against "multi-faith mish-mash" in the UK.
He told BBC Radio 4's Today programme the monarchy and the legal system had both emerged from the Judeo-Christian ethic.
'Values come from the Bible'
Born a Muslim in Pakistan, Dr Nazir-Ali said: "All our values come ultimately from the Bible.
"People of other faiths recognise this and they are not often the ones asking for a multi-faith mish-mash. They recognise the value of Britain being a Christian country."
The Prince of Wales first expressed a wish to become "Defender of Faith" rather than "Defender of the Faith" in an interview in 1994.
He suggested the title held by all British monarchs since Henry VIII implied they would protect only Christians.
Dr Nazir-Ali said he would have no issue with the prince wanting to uphold the freedom of people of every faith.
He added: "But you can't defend every faith, because there are very serious differences among them."
Dr Nazir-Ali blamed "secularisers" for creating pressure to remove the distinctively Christian character from places like hospital chapels.
Speaking about a specific example of such a trend, he said: "The people it does offend are the secularisers who want to level us down to a lowest common denominator, so that faith doesn't make any impact on society whatsoever."
Several other prominent figures in the Church of England have also expressed concerns about the erosion of Christianity in public life.
The Archbishop of York, John Sentamu, has called for the British people to remember their Christian heritage.
Meanwhile, former Archbishop Dr George Carey has said he has concerns a minority in leadership want to privatise religion.